Printing telegraph system



J. D. DURKEE PRINTING TELEGRAPH SYSTEM Get. 7, 1952 3 Sheets-Sheet 1Filed Jan. 23, 1950 o .w v.

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IIII 5 Patented Oct. 7,

UNITED STATES PATENT OFFICE 2,613,267 PRINTING TELEGRAPH SYSTEM James D.DurkeaFairlington, Va.

Application January 23, 1950, Serial No. 139,977

Claims. 1

My invention relates broadly to printing telegraph systems and moreparticularly to a high speed polarized system of printing telegraphyutilizing printing telegraph apparatus of compact size and light weight.

One of the objects of my invention is to provide a printing telegraphsystem constituting an improvementupon conventional sequentiallyoperated systems, overcoming inherent difficulties in these systems. I

This invention covers a printing telegraph apparatus and system which isself-synchronizing, requires less channel band-width than existingmethods, provides means for indicating when impulses are lost orobliterated by fading or interference and is capable of increasedtransmission speeds and yet employs less equipment even when adapted toequipment and systems presently in use.

This achievement is made possible bythe invention of a polarizedelectrical matrix which requires "the transmission of only" fivepolarized pulses, Without the necessity 'of transmitting start-stoporsynchronizing pulses, to accomplish the thirty-two differentpermutations andcombinations of signal impulses presently used inprinting telegraph systems.

Since in my "application a smaller number of permutationsand'combinations of signal pulses are required to produce the samenumber of permutations and combinations as used incur;

rently existing systems, a "greater number of permutations andcombinations can be sent in less time with fewer impulsestherebyrequiring a smaller number of transmission bands and lessfrequency band-width.-

In addition, since the system of my invention requires only a reversalofcurrent direction or polarity, the transition from one polarityorphase to the opposite polarity or phase may be accomplished bysinusoidal wave form; thus, the impact excitation resultingfrom a rapidmake or break keying operation or from a rapid frequency shift iseliminated, thereby further decreasing the key ing band-width requiredat any speed of trans mission. l

A further object of my-invention is to' provide- .a self synchronizingreceiving system which may be made operable over a fairly wide range oftransmissionspeeds'and Which requires a minimum of equipment oradjustment.

Another object of my invention is to provide means for supplying a pulseor pulses which may have {bee'iilost intransmission or obliterated byinterferenceand means for indicating on the receiving copy a mark orsymbol which visually indicates that the character received isincorrect.

The apparatus described in this application is intended for use with anelectric typewriter or with slight modification of the present printingtelegraph systems may be used interchangeably with conventionalequipment.

My invention will be more fully understood from the specificationshereinafter following by reference to the accompanying drawings in whichFigure 1 diagrammatically shows the transmission system of my invention;Fig. 2 is a schematic plan view of a fragmentary portion of thetransmission keyboard; Fig. 3 is a schematic and elevational view of thetransmission keyboard, the View being taken on sectional line 3-3 ofFig. 2 and showing the frame structure in vertical section; Fig. 4 showsthe receiving circuit of the printing telegraph system of my invention;Figs. 5 and 6 are detail views illustrating the operation of the controlmechanism in the receiving apparatus; Figs. 7 and 8 are detailed viewsof the operating solenoids controlled by the printing telegraphreceiving system; Figs. 9 and 10 are enlarged schematic views showingthe operation of the error indicating means employed in the receivingsystem of my invention, the views being shown in front elevation andwherein Fig. 9 shows the error indicating means in printing positionwhereas Fig. 10 shows the error indicating means released and free ofprinting position; and Fig. 11 is an end View of the error indicatingmeans shown in Fig. 9.

cated that greater reliability could be placed on mechanical resolutionand the present state of the art reflects this experience. Mechanicaloperations, however, have the inherent characteristic of requiring alonger time to perform the same functions than does electrical energy.

However, operational communication requirements forincreased speeds ofoperation have now exceeded the capabilities of the mechanical equipmentexcept under strained and abnormal conditions which require excessivmaintenance and mechanical tolerances and precision of apparatus whichare difiicult to achieve.

The application of printing telegraph systems to radio communicationalso introduced additional difiiculties which do not readily lendthemselves to solution by mechanical methods due to the speedlimitations of mechanical operations.

Two of the major difliculties introduced by radio communication arevarious forms of fading and interference in addition to the basiclimitation in the number of cycles available in the total radiofrequency-spectrum;

Heretofore, various approaches to the radio applications of printersystems have been by increasing power of transmission and improvingreceiving conditions in an effortto'duplicate the operating reliabilityof a land line-toovercome fading and increasing the dot cycles ofoperation by additional fail safe impulses'or increasing the units ofthe basic five unitcode to provide error detection resulting frominterference and certain forms of fading.

The approach of 'my' invention'to the solution of the requirement forincreased speeds has been to'eliminate the basic mechanical limitationof the mechanism used to'resolve the units of the five unit code intocharacters by use'of a polarized electrical matrix; to decrease theelectrical contacts required to 'a minimumby' use of rectifyingapparatus and the application (knew and novel electrical circuits and todecrease the operational functions to a minimum bysimplification ofequipment and electrical circuits.

The fading and interference problems introduced "by radio'c'ommunicationhave'bee'n accepted as natural characteristics of the medium. Circuitsand operations are provided by my invention which take these naturalcharacteristics into'account and pro'videsubstitute characteristics inthe form of locally produced impulses to replace those 'lost intransmission due to fading or to counterbalance impulses introduced intransmission as a resultof interference and to indicate on the receivingequipment when these functions have been required to complete theformation of a character In endeavoring to achieve greater economy ofbandwidth, the start-stop or synchronizing impulses heretofore 'used' inboth radio and wire methods have been eliminated in my invention byself-synchronizing apparatus resulting in an approximate savingof twentypercent of I handwidth-required to perform the functions necessary tothe formation-of a character as compared to systems which transmitstart-stop impulses or synchronizing impulses.

My inventionemploys apparatus and methods which are compatiblewith'existing methods" and apparatus, allowing in almost every-instance,- the use, "with slight modification, orexisting equipment'andmethods to accomplish '-its-purpose.

Transmitting apparatus Figs. 1, 2 and 3 showthe transmission-system ofmy invention, the transmitting keyboard-being shown in plan view in Fig.2 and in'end-vlew in Fig. 3.

When the key I ,pivotally moun-ted'at la, is depressed, bars 2, 3, 4, 5and 6 which extend therefrom depress lever l, 8,-9,-|0:and .I I in adownward'direction to form contact with the contacts [2 to 2|. Thelevers 1-l lare supported atopposite ends in frame N6 of thetransmitting keyboard as shown at la and lb; 8a--and'8b; 9a and 9b; Illaand 10b; and] la. and I lb through resilient self restoring flexingstrip members l lal lb. Contacts I 2-2l are insulatingly supported inrelation to frame I46 in alignment with the pivoted levers 7-1! asshown. The levers l-ll are normally biased by the resilient selfrestoring flexing strip members 1a''lb'; 8a'8b; 9a'9b'; llla'l0b'; andHal-lib, to a position in horizontal planes and flex under the pressureof the bars 245 in either a clockwise or a counter-clockwise directiondepending on the relative positions of the bars 2-:6}with respect to thecenters of levers l-l I, for effecting momentary contact at I2-2l. Whenpressure of I bars 2-6 on the levers 1-H is removed the levers 'l-l larerestored to horizontal position breaking thecontacts'l2-2l by theselfrestoring action of the flexing supports at each end of the levers 1-H.The contacts which are formed depend upon which side of the center oflevers 1 to H,

tact through l2,'and the contact'carried" by lever I to stepping relaycontact 22 through'arm 21 through relay coil 3!) to the center tap 29aof battery 29. Thecurrent in coil 30 caused armature 3| to move down,making contact withflcontact 32 which in turn caused the'armature 33 ofstepping relay'28 to be moved down because of the current in relay coil34 produced by closing of contact 32. The movement ofarmature 33 causedratchet arm '35'to pull arm 21 away from contact 22 counterclockwisetowards'stepping relay contact 23. During the time the arm 21 was incontact with contact 22, a positive voltage was applied to line 36 withrespect to' ground or center tap 29a of battery 29, or was caused toflow through rectifier 38 through relay coil 38a in a positive directionresulting in movement of arm '39 of relay 40 to make contact at .43which in turn keyed the marking frequency of afrequ'en'c'y shift radioprinter keying circuit.

As soon as arm 21 left contact 22 the-current in relay-coil 30 wasreleased and contacts 3| and 32 were opened de-energizingcoil'34 of thecontinuously cycling spring driven stepping relay'28 which inturnrepositioned ratchet arm 35 preparatory for another ratchetingoperation.

The capacity 4| and adjustable resistor 42 across coil 34 acts to retardthe arm 21, sufficiently long at each contact 22 to 26 to permit-thefull cycle of operation previously described to be completed. I

When arm 21 arrived at contact 23 the same cycle'of operation was set inmotion as when the arm 21 was at contact 22, except that the charge ofvoltage on contact 23 is now derived'from the negative source of battery29, thru the-contact on lever 8 and contact l5 and a negative charge wasplaced, thru rectifier 31 andrelay coil 31a to ground or-center tap -29aof battery 29,.causing armature 39 toclosecontacts 44 keying the spacingfrequency ofthe frequency shift keying system or causinga-negativecharge to be placedon line 36. v

The same cycle ofoperation-is repeated at stepping relay contacts-24, 25and 26 resulting in moving arm 21 back to-the originalposition incontact with contact22 having thus completed a transmission cycle offour self-cycling operations from contact 22 to contact 25 whichresultedin sending four equally spaced pulses and one starting pulseofalternate positive and negative .charges to a line or causing the two.frequencies' of a frequency shift keying system to .be

alternatively operated causing five pulses divided between two differentalternating currents to be transmitted.

I Since the pulse caused to be transmitted when arm 21 is incontact withcontact 22,is the start-'- ingpulse, it does not have to be especiallyspaced in relation to any previous pulse. The pulse created bycontact ofarm 21 with contact 26 is the end of the character formingcombination.

Figs. 2 and 3 show the arrangement of the transmission. keyboard moreclearly from which the coaction of the pivoted keylevers 45 with thecontact control means will be understood. ,-;The,

key-levers are, arranged above the angularlyshiftable levers 1, 8, 9, Iand II and through bars 2, 3.14,- 5 and 6 selectively control theangularv movement of the levers about their; pivotsfia, 1b-IIa, III),that in ,turn'control the contact I2, I3, I4, I5, I6, I1, I8, I9, and2Ifor,,controlling the circuits heretoforedescribed. 1

When arm21 arrives atcontactZB, curren from negativeabattery' 29 flowsthrough coil 46, arm 2.1;and;coil. 30 to the center tap 29a of bat-When, armature 66 made connection with con? tact 61, extension rod 66aconnected with operating spring 662) the continuity-of the circuit I41to, arm 6| was broken between spring Iitband contact 650, insuringagainst the possibility of aprolonged pulse causing a false operationprior to the completion of the pulse. duty cycle. This also. permits thecarrier or signal current to be maintained in an on condition during theinterim between the formation of signal characters.

When current was passed through relay; 53,

armature 18 caused extension bar 19 to pull con,-

tactsSIl to 81 into connection withcontacts 89,.

Q0, 9I,,92, 53, 94, 95 and 96.

Upon arrival of arm 6| at contact 51 the clr-i cuit from line I41through rectifier I34 to line 55 tery 29. This causes armature 41 tobeattracted bythe electro-magnetic core of coil 46 making contactat45,;permitting current to How through coil 49 from-positive battery 29tonegativebattery .29. ;When,coil 49'shown more clearly inFig. 3wasenergized armature 59 was drawn towards the electro-magnetic core ofthe coil 49 pushing oscillating bar 59 against armature 5| releasingpressure of point 5Ia of pivoted-member5| on. roller 52 carried by theend of keylever per-5 mitting spring 53 to pull keylever 45 up againststop 54 which action lifted key bars 2, '3, 4, .5 and Birom bars 1, 8,9, I9 and II, allowing the latter to resume normal position. Thuspermutations and. combinations of signal pulses canbe formed andtransmitted by contacts 43 and 44 under selective control of thekeyboard as described.

Receiving apparatus Fig. 4 shows the receiving circuit ior the receivingprinter of my invention. Th 'permutation and combination incoming signalpulses, whether received by line or as a result of rectification of aradio or audio frequency current, appears on line I41 of Fig. 4 as apositive or negative voltage with respect to ground 55in accordance withthe manner inwhichitwas I transmittedby the apparatus described in Figs.

1 3. The current flows through the stepping arm 6| of cycling switch 62to contact 56 and the winding of relay 63 and, if the voltage is ofpositive polarity with respect to 55, which is the center tap 29a ofbattery 29 from which the voltage on line I41 is derived, through arectifier 64 to line 55. The current also flows through coil 85'from'line I41 to line 55.

When current passed through coil 65, armature Iifimade connection withcontact 51 completing the circuit between positive battery 29 and coil68 andground 55. This moved armature 69 to the left causing ratchet arm10 to turn ratchet wheel 1|, which caused arm 6| to move from contact 56to contact 51, and through shaft I45 caused arm 12 to move-from opencontact 13 to contact '14.

is completed. If the voltage on line I41 is now negative, rectifier 54will not pass current.

through relay coil 91 to ground 55 and thus ar-.

mature-99 remains in position shown and con tacts to I02 are not broken.

The current through coil 55 again caused the arm 5|, as a result of theaction similar to that previously describedto move to contact .58. Ifthe voltage in line I41 is now positive with 're-' spect to ground orcenter tap'29a of battery 29 and the circuit is completed from line I41through arm 5i, contact 58, coil I03, to rectifier 54, and line 55, thecurrentfiow through coil I93, caused armature I I 94 to move bar I55causing leaf. spring contacts I95 and I51 to connect with con- 'tactsI03 and I99. 1

'When arm 5i arrived at contact58 the action resultingfrom currentaction in coil-55 was again repeated causing 6| to move to contact 59and arm 32 of the stepping switch I32'to move toccn tact 16.

The arrivalof arm 5| at contact 59 completed the circuit from line I l?through coil IIU, arm 5| contact 59, to rectifiers 64. If the voltage isnow negative, rectifier 64 will not passv current throughcoil IIEI toground 55 and armature III and bar I I2 remain in the position shown.

The cur-rent in coil 55 present when contact 62 I of arm BI is incontact with contact 59 caused arm 5 I to-move to contact 55 and arm 12to-move to contact 11.

Line I41 is now connected thru arm 5 I, contact I 55 and contacts H3,I91, I09, IIII, and 94, to

theprinter magnets N and SP, to rectifiers II4 and I I5 to line55through lead 55a.

If the voltage in line I41 was positive when contactwas made by arm GIat contact 69, a.

positive current will now pass through the printer magnets N (Fig.4) andrectifier I I5 to and by the process described above. This willcause the1613-. ter N of the printer to print.

When the letter N function was activated by the action-of arm 5|contacting contact 60, current also passed through relay coil I I6 inthe lead 55a which caused armature I I1 to unlatch armatures 19, 94,IIM'and III of relays 53, 91, I03 and H5. preparing the system toreceive a new cycle of character forming impulses. v

Examination of Fig. 4 will show that, predicated upon the polarity ofthecurrents in line I41 with respect to line 55 as presented to the matrixshown in the lower right hand portion of Fig. 4 in sequentialcombination and with the use of pressure roller springs H8, H9, I29 andI2I' to latch armature 18, 95, I04 and III in a fixed position for aperiodcovering the cycle of operation, it is possible toindividuallyselect any one of the multiplicity of magnets in various.permutaf tionsand combinations represented by reference "Let"designating fLetters-to Blk designating Blank of 'Fig. lslnFigs. and 6'Iihave shown thetwo limitingipositions of armature III on an enlargedscale 'to illustrate the two extreme latched'positionsthereof undercontrol-of pres- I sure roller spring II8. Alliof the armatures .18, 98,I94 arearranged in-a mannerisimilar to armature- II I, that .is thearmaturesl8, 98 and I04 are controlled in their limiting positions bypressure roller'springs- I2 I, I and I I9 respectively.

Figs? and 8 are enlarged views of the solenoids in thepolarized matrixcircuit wherein Fig. 7 represents the .juxtapositions of the operatingsolenoids for letters W- and A and letters Z and E whilelFig. 8' showsthe electricalequivalentof the same juxtapositioned solenoids.

The. capacitor-resistor combination I22 and I23;:are used to control thedissipation of current in condenser'I22 through coil 68 after-opening ofthe circuit to battery 29 by the operation of relay 65 and which in turncontrols the length of time in which arm 6| moves from one contact tothe other of the group of contacts 56 to 60.

Under certain conditions of operation particularly in radio circuits thepossibility of loss of one ormore impulses due to fading or obliterationof signals by interference is always present.

To-overcome this conditiomprovision has been made in the selector systemfor the supplying of lost impulses and recording this circumstance onthe printed copy. The effect of interference is made to appear as a lostimpulse in this system.

Each time that the armature 66 is in contact Withcontact I24 in additionto holding armature I25 in contact with contact I26, battery 29 chargesthe condenser resistor delay network I21 and I28 across coil I29. Eachtime the armature 66 is opened by removal of energy from coil 65,contacts 66 and I24 are broken which opens the circuit from positivebattery 29 to negative battery 29 through coil I29. When this occurs theenergy stored in capacitor I21 starts discharging through resistors I28and I28a into coil I29 holding armature I25 that is in circuit withcondenser I30 through contact I26 to battery 29.

-If no voltage appears on line I41 for. a fixed period of time aftercontact has been established by arm 6I with any oneof the contacts 51,58, 59 and 60 before the dissipation of energy in condenser I2! iscomplete, armature I25 will'be released from contact I26 and contactwill be established with contact I3I allowing condenser I30 to dischargethrough resistor I3I3a, coil I32, arm I2 and contact 14, I5, I6 orlI ofa duplicate bank of contacts on the same shaft-as contact arm 6I to lineI4! through which ever circuit arm 6| provides through its contact withcontacts 56 to 60, thus producing the same action which would haveresulted from an incomingsignal on line I41. 7

When this current passed through coil I32 the armature I33 was movedandclosed the circuit through contact I33a connecting battery 29 to a relayI34 associated with the printing mechanism.

When the relay I34 was energized, the armature I35 was attracted to thepole of coil I34, latching itself to latching armature I36 and bringingthe extensionwire 131 of armature I35 acrossthe surface of the characterA for exampleon the type pallet I38 which may strike the ink-ribbon I39of Fig. 11 and beprinted on the paper web I40 being advanced on, platenI4I of the printer as shown more clearlyin Figs. *9 and 10, and 11.

Fig. *9 shows theconditionfor indicating error while wFig. 10 shows anall --'clear condition with the error indicator removed.

When relay II6 was energized contact was made between I44 and Ill,placing battery on coil I42 which caused armature I36 to releasearmature I35 allowing spring I43 to draw-armature I35 to its normalposition'with the extension I31clear'of the printing surface of the nextcharacter placed in-a printing position.

When the latter key is operated to. printithe character formed, partlyby the self-imposed impulses of condenser I30,- the character which .isprinted will be-' marked by a vertical bar stroke by the extensionbar'I3I of armature I35plainly indicating'to the-operator thatthe'character was not properly received.

tacts of Fig. 4can be'connected to'a series of so1enoids or magnets andbe used to operate an electric typewriter 'Or. initiate the printingmechanism of other types-of presently used printin'g telegraph.equipment. 1

Conventionali'printer mechanism is operated by the solenoids lettersthrough blank shown in the polarized matrix in the-lower left'corner ofFig.2.

Due to the fact that thenecessityfor amechanical selector is eliminatedin the printer-system of my invention and yet very accurate and quickmovement of=the selection system of my inventionobtained by use ofpositive and negative electrical impulses, I am able to reduce the sizeand weight of the equipment, as compared to conventional equipment, Ivery materially.

The receiver and transmitter with which the system of the instantinvention operates are set forth in my copendingapplicationsfor-"Letters Patent-Serial Numbers 228,657 and 228,658, bothfiled May 28, 1951.

While I have described my invention in certain of its preferredembodiments I realize that modifications may be made and I desire thatit be understood that no'limitations upon my invention are intendedother than-may be imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of theUnitedStates isas follows:

1. In a printing telegraph system, a type bar printer including at theprinting position-thereof a platen for supporting and advancing theprinter copy, a printing ribbon aligned with said platen at the instanceof striking of the printer copy by a type bar,- an-error indicatordevice movable into the path of impact of the typebar with theprintingribbon and the printer copy for indicating failure of receipt of therequiredsignal code impulse permutations and combinations for effect-'electromagnetically actuatedby failure of receipt of therequiredsignal-code impulse. permutations and combinations.

3. Aprinting telegraph system asset forth in claim 1 in which the errorindicatordevice is else-- tromagnetically positioned in the path ofimpact of the type bar upon failure of receipt of the requirecl signalcode impulse permutations and combinations and in which an additionalelectromagnetic device is located adjacent the error indicator devicefor restoring said indicator device to non-alignment with the impactpath of the type bar when the required signal code permutation andcombination for the particular character in error is corrected.

4. A printing telegraphv system comprising in combination with a typebar printer including at the printing position thereof a platen forsupporting and advancing the printer copy, inking means aligned with theplaten at the instance of striking of the printer copy by the type barand means for interposing an error indicator in the path of an actuatedtype bar, said inking means a and said printer copy so long asincomplete signal code impulse permutations and combinations arereceived.

5, A printing telegraph system as set forth in 4 claim 4 in which meansare provided for remov-' ing the error indicator from the path of anactuated type bar, said platen and the printer copy concurrently withthe restoration of the complete signal code impulse permutation andcombination for the character intended.

' JAMES D. DURKEE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date r 1,737,024 Roe Nov. 26, 19292,304,120 Potts Dec. 8, 1942 2,353,327 Warwick July 11, 1944 2,471,473Young May 31, 1949 2,498,695 McWhirter Feb. 28, 1950 2,516,936 YoungAug. 1, 1950

